Allen Park — Young NFL players develop at different rates, but a commonly held belief among the league’s decision-makers is you have a pretty good idea what you have by the third season.

For that reason, you have to be cautious about giving up on a player too soon. Detroit Lions fans were reminded of that lesson last year with center Travis Swanson, who after an underwhelming start to his career, was one of the team’s most consistent offensive linemen in 2016.

This year, nickelback Quandre Diggs is looking for a similar breakout after expectations were tempered by a sluggish sophomore campaign.

A sixth-round pick in 2015, injuries thrust Diggs into a starting role during the early stages of his rookie season. He responded well and exceeded expectations, putting him in prime position to hold the role the next several years.

But he took a noticeable step back last year, failing to capitalize on his early momentum. He particularly struggled in coverage, allowing 34 completions on the 38 passes where his coverage assignment was targeted, according to STATS LLC.

“Last year was really a kind of eye-opener in terms of how he played,” defensive coordinator Teryl Austin said. “He didn’t play very well, and I’m sure if you asked him, he’ll tell you that.”

Diggs finished the season on injured reserve, suffering a pectoral injury in Week 13. After he went down, things arguably got worse at the nickelback spot. The team turned to a combination of undrafted rookie Adairius Barnes and late-season addition Asa Jackson. Neither played the run as well as Diggs and the coverage issues in the slot remained.

Wary of a repeat performance, both from the starter and the depth, the Lions aggressively pursued upgrades at nickelback this offseason. First, the team signed former first-round pick D.J. Hayden to a one-year, incentive-laden contract. A month later, they drafted Jamal Agnew, a small-school standout with a knack of getting his hands on passes while also offering some intriguing potential as a return man.

It’s easy to draw comparisons to Swanson a year ago. When the Lions drafted Graham Glasgow in the third round, it was assumed the rookie was being brought in as a replacement for the young veteran. In the end, Swanson put together a strong offseason and the camp battle quickly turned into a lopsided affair.

The Lions are making sure they’re covering all their bases. If, by Year 3, these young players aren’t turning a corner, they want options. That’s what Hayden and Agnew represent.

But in the cauldron of competition, Diggs has thrived. He’s looked the sharpest of the three on the practice field, and he’s also stood out in the early preseason games, both on defense and special teams. Although the starting job remains up for grabs, he hasn’t done anything to cede pole position.

“He’s played tough, and he’ll make you notice him real quickly, both in the kicking and also from scrimmage,” coach Jim Caldwell said. “He’s always been a real heady player, smart, and not only that, he can trigger and tackle, which you can see. I think, he's really done a nice job thus far this year.”

Diggs shrugs off the idea he’s elevated his game in the face of the new competition. As far as he’s concerned, he’s been an underdog since the day he was born, having to live in the shadow of his bigger, more athletic older brother Quentin Jammer. A star safety at Texas, he was the No. 5 overall pick in 2002 and played 12 seasons in the NFL.

“People always expected me to do something,” Diggs said.

To Diggs, he’s just overcoming the trials of youth. He’s quick to remind you that he was only 23 years old last season. This year, everything is lined up for a breakout — he’s more experienced in the scheme and there is continuity in the secondary — and he just needs to answer the bell.

“He’s really looked a lot more like the player that played that first year for us, really around the ball, active, physical, doing a lot of really good things,” Austin said. “I think he’s risen to the challenge.”